Electra-optic materials such as for example, but not limited to gallium arsenide (GaAs) and lithium niobate (Lib03) are employed in wide range of electronic/photonic processes for processing optical signals. The electro-optic materials can change their optical properties in response to an electrical effect. Such materials are widely incorporated within the electronic devices for use in the telecommunications field in order to perform processing activities such as, for example, but not limited to, optical signal switching, the modulation of optical signals, the demodulation of optical signals and the compensation of optical signals for dispersion effects that occur during the signal transmission.
Typically, the electro-optic materials are incorporated within a ridge waveguide structure in which the ridge waveguide guides are designed to substantially contain the optical signal. The electro optic material can either be located within a slot within the ridge waveguide, or can be used to form the ridge waveguide. The ridge can be either freestanding or embedded within another material.
A slotted waveguide is especially useful for making impedance measurements. A probe extends through the slot into the waveguide for detecting the intensity of the radio frequency (RF) field at the tip of a probe supported by a carriage on calibrated ways. The distance between a maximum and adjacent minimum is an accurate measure of the wavelength of the RF energy inside the waveguide with the ratio of the maximum to the minimum being representative of the VSWR of the circuit to which the slotted line is coupled. For performing accurate measurements the VSWR of the slotted waveguide itself should be as near to unity as possible. At higher frequencies where the span of the waveguide cross section is physically small, it has been difficult to achieve the desired high accuracies.
Most of the prior art methods for fabricating the strip loaded waveguide are very slow and impractical for growing waveguide structures that are compatible for a wide range of electro-optic modulations. Further, the prior art processes may increase the amount of contaminants in the waveguide structure. Such contaminants may also contribute to optical losses in the waveguide structure.
Based on the foregoing, it is believed that a need exist for an improved asymmetric strip loaded slot waveguides for electro-optic modulation. A need also exists for an improved method for fabricating the asymmetric strip loaded slot waveguide using a CMOS process, as described in greater detail herein.